Pakistan and India hate each other — they're like two high school cheerleader frenemy types.
Pakistan is messing around with Afghanistan because it wants a buffer against India — so Afghanistan is kind of like the hapless geek-boy who gets manipulated by all of the girls. The USA is the popular but dumb-as-rocks jock who need geek-boy Afghanistan's help to get passing grades. In order to do so, the USA is courting Pakistan like she's the only pretty girl in town. Which is dumb, because Pakistan is all, like, "whatevs." What the USA *should* be doing is playing Pakistan against India. Like, the USA should be all "What's that Pakistan? You won't put out? And you won't stop messing with Afghanistan? OK then, I'm not taking you out to Prom [i.e. spending millions on your military], and you know what, maybe I'll ask India out to the Prom instead! And maybe India and I will totally make out under the bleachers — what do you think about that?"

We do that, and I guarantee you Pakistan will come around real quick. That stupid manipulative cheerleader bitch.